1. Field of the Invention
The present invention relates to a portable device such as a cellular telephone.
2. Description of the Related Art
With the technology of portable devices including cellular telephones improving at a rapid pace in recent years, portable devices have come to be utilized for various purposes. For instance, it is becoming popular to view video content and listen to music content on a cellular telephone or equipment connected to the cellular telephone.
Also, various short-range wireless transmission systems intended for a transmission distance up to several tens of meters have been developed. With such a short-range wireless transmission system, a method of transmitting music data and the like at home, for example, has been in put into actual use. Bluetooth (trademark) is an example of this method.
By using a given profile defined in short-range wireless transmission technology, music data can be transmitted and received between a portable device such as a cellular telephone and an external device such as a headset.
In relation to this method, Jpn. Pat. Appln. KOKAI Publication No. 2005-347839 (Yamada) discloses a music data transmitting device and a music data reproducing device for suppressing sound skipping caused by a data underflow in the music data reproducing device.
According to Yamada, when receiving a retransmission request signal from a music data reproducing device while the received data is not in a favorable condition, the music data transmitting device resends the designated music data, for example, L-channel data out of the requested frame of data. Based on the sound levels of both L and R channels immediately before the resending request and the resent L-channel data, the music data reproducing device generates R-channel data based on the resent music data and the sound levels. Then, the music data reproducing device outputs a music signal corresponding to the L-channel data from the speaker L, and outputs a music signal corresponding to the R-channel data from the speaker R.
The technology disclosed in Yamada thereby suppresses the underflow of data in the music data reproducing device.
A portable device such as a cellular telephone has a large variety of functions unlike an ordinary device dedicated to music reproduction. Thus, the following problems may arise when the music content reproducing process conflicts with other processes.
For example, when audio data of music content is transmitted from a cellular telephone to a headset by means of Bluetooth communication, an underflow of audio data may occur in the cellular telephone. This causes annoying skips in the sound output from the headset. Furthermore, a similar problem arises when the content transmitted from the cellular telephone to the headset includes motion video content containing video data in addition to audio data.
Yamada, however, neither discloses nor suggests such problems or a means :for solving the problems.